Originally posted by Robert Morin It was so long ago (8years) that I can't remember the B+. The 1h4 was cathode biased. The sound was VERY clear just not lively.

Robert M.

Wait!!! What am I saying! the 1h4 is a DHT - IE no cathode I can'y really remember what I did but I remember useing those 2 volt battery tubes and being impressed at first but later not being happy with the dynamic performance. They would make a good "sanitizer" for recording things like Bass and drums though.

The one thing I really learned from that amp, besides how anoying HUM can be, was how much the sound depended uppon the passive components. It was a simple design, and the bypass cap on the cathode alone had a huge impact. Use a crappy BP-cap (or coupling cap..), and it will indeed sound compressed and soaked!
My first choice at the time was a Panasonic Low Impedance type. Later I got some Sanyo OS-CON's, and I was amazed! It seemed like I had been listening to the bypass cap, and not the tube! And even better it got when I got some Elna ARD series caps!

I guess one needs top-of-the-line parts if one wants to make these tubes sing.

My first sound test with that amp was on a NAD 340, connected it straight to the power amp, on to B&W monitors. I never used the transistor preamp inside the NAD again (well, not as long as I had that NAD... I would describe it as very clear from top to bottom, sparkling and veil-lifting. Far from 'compressed'.

But, with that said, must admit I have never heard other DHT's like the 26, or IHT's like the 27... so... heh.... bye!

Back to the tubes...
a) Let me say this - usually, when I hear someone say "all ____ tubes sound _____" they are wildly generalizing, often from a single experience. I've breadboarded #30's, #112's, #01's, #31's many times now, and never had a bad experience.
Hum is a non-issue, since they have such low gain, and use DC filaments. And the sound was as full-range as any other tube I've wired up. I think they're relatively tough, very forgiving tubes, and easy to work with. This is contrary to the popular belief - 90% of whom don't own any of these tubes.
b) All the early tubes were designed to be operated with fixed bias, and you will do yourself a big favor by running them this way.